Communication between on-premises and off-premises platforms occurs in a Software as a Service (SaaS) environment. SaaS is a software licensing and delivery model in which software is licensed on a subscription basis and is centrally hosted by an off-premises platform (such as a shared computing resource or a cloud computing resource accessible via the Internet for example). SaaS is typically accessed by users of an on-premises platform (for example, using a thin client via a web browser).
On-premises platforms are well-established and considered to provide a good level of security because data is stored and handled internally, e.g., within an internal private network.
Off-premises platforms (such as cloud computing resources) are a relatively recent and evolving concept. Generally, reference to off-premises resources or platforms is taken to refer to a concept for enabling ubiquitous, convenient, and on-demand access via Internet to shared pools of configurable off-premises (e.g. remotely located) computing resources such as networks, file systems, servers, storages, applications, functionalities, and the like which are accessible via the Internet. Conversely, reference to on-premises resources or platforms is taken to refer to a concept of local or private computing resources such as networks, servers, storage devices, application, etc. that are situated locally or within/behind a virtual boundary (often behind a firewall).
Due to the communication between on-premises and off-premises platforms in a SaaS environment, data file systems in a SaaS environment frequently need to integrate with systems of record within a datacenter behind a firewall. Typically, this is done by using Virtual Private Network (VPN) technology. To set this up is complicated and has security issues (because the VPN technology has the potential to expose more access to the end system than just a directory in a file system). Also, the nature of cloud computing is that systems needing access to a file system (and systems providing the file systems) can be highly dynamic with systems being repeatedly and/or continuously destroyed or recreated.